Acorn 5.4+ includes a scripting interface for replacing editable text in your image.

For Applescript:

tellapplication "Acorn"

telldocument 1

replacetext "$foo$" with "This Is The New String"

endtell

endtell

For Javascript:

doc.replaceOccurrencesOfString_withString("$foo$", "This Is The New String");

Combine this feature with pre-made templates and you can automate the making of templates, guest tags, or anything else that combines lists of text with images. See below for an example that starts with a simple template. Applescript drives the text replacement along with saving the images as PDF.